Biocidal compositions, which may be, for example, germicides, antimicrobial or antibacterial blends, are widely used in different industries, hospitals and institutions as well as in consumers' daily lives to inhibit or kill various microorganisms, including bacteria, viruses, fungus, protozoa or other susceptible pathogenic agents (collectively “biocidal targets”).
In the United States (US), the Environmental Protection Agency (EPA) tests biocidal compositions using an AOAC (Association of Analytical Chemists) Use Dilution Test (UDT) to determine if a biocidal composition has the disinfectant efficacy claimed. The UDT is a probability based test that determines if a specific contact time, e.g., 5 or 10 minutes, of a test biocidal composition shows no growth for a particular biocidal target, where a pass is at least 59 out of 60 UDT test samples showing no growth. 59 or 60 out of 60 test samples showing no growth ensures a statistical significance of greater than 95% that the test composition will eradicate the bacteria of the inoculum. The criteria for acceptable performance are currently under review at the EPA. A proposed passing criteria being contemplated for the UDT would allow for growth in 3 or less test samples out of 60 to pass. If the proposed changes are accepted, biocidal compositions resulting in no growth in at least 57 or 58 or 59 or 60 out of 60 test samples will successfully demonstrate disinfectant efficacy. Yet another method that is being evaluated at present to possibly replace the UDT in the US at a future date is the OECD Quantitative Test Method for Evaluating Microbiocides on Surfaces which is a quantitative method for evaluating bactericidal activity of microbicides used on hard non-porous surfaces. The proposed criteria for compositions to be able to claim biocidal efficacy is that they need to demonstrate a 4 log10 to a 5 log10 reduction in number of specific target organisms such as Pseudomonas aeruginosa (Pseudomonas), Staphylococcus aureus (Staphylococcus), Salmonella enterica (Salmonella), etc. Alternately efficacy of biocidal compositions is measured by tests such as EN 13697, Quantitative Non-Porous Surface Test for the Evaluation of Bactericidal Activity of Chemical Disinfectants Used in Food, Industrial, Domestic and Institutional Areas in Europe. The European standard is a quantitative method in which an efficacious biocidal composition has to demonstrate a minimum of 4 log10 reduction in number of the target organism.
The industrial standard microbial contact kill time as determined by the EPA-approved Use Dilution test (UDT) for a bucket dilutable composition for major biocidal targets, e.g. Staphylococcus aureus, Salmonella enterica, Pseudomonas aeruginosa, etc., is 10 minutes. In other words, for a bucket dilutable disinfectant composition to claim disinfectancy of hard surfaces, the composition must pass the 10 minute contact kill time. There is still a strong need and unforeseeable solution in the art for biocidal compositions that provide shorter contact times (i.e., faster rates of kill, e.g. 5 minutes or less), a broader spectrum of activity, and/or a wider range of applications (e.g., hard surface disinfectants). There is especially a need for more efficacious biocidal products in the disinfectant field to reduce the kill time for problematic biocidal targets in hospital settings, e.g. Staphylococcus aureus, and Pseudomonas aeruginosa, to provide shorter contact times and thus reduce the likelihood of creating superbugs or bacteria resistant to disinfectants.